<!DOCTYPE html>
<html lang="en">
  <script>
    var _hmt = _hmt || []
    ;(function () {
      var hm = document.createElement('script')
      hm.src = 'https://hm.baidu.com/hm.js?c923daf3182a4b0ce01878475080aadc'
      var s = document.getElementsByTagName('script')[0]
      s.parentNode.insertBefore(hm, s)
    })()
  </script>

  <head>
    <meta charset="UTF-8" />
    <title>甜甜，生日快乐！</title>
  </head>
  <style>
    body {
      margin: 0;
      overflow: hidden;
      background: black;
    }
    canvas {
      position: absolute;
    }
  </style>

  <body>
    <canvas></canvas>
    <canvas></canvas>
    <canvas></canvas>

    <script>
      function GetRequest() {
        var url = decodeURI(location.search) //获取url中"?"符后的字串
        var theRequest = new Object()
        if (url.indexOf('?') != -1) {
          var str = url.substr(1)
          strs = str.split('&')
          for (var i = 0; i < strs.length; i++) {
            theRequest[strs[i].split('=')[0]] = unescape(strs[i].split('=')[1])
          }
        }
        return theRequest
      }
      class Shard {
        constructor(x, y, hue) {
          this.x = x
          this.y = y
          this.hue = hue
          this.lightness = 50
          this.size = 15 + Math.random() * 10
          const angle = Math.random() * 2 * Math.PI
          const blastSpeed = 1 + Math.random() * 6
          this.xSpeed = Math.cos(angle) * blastSpeed
          this.ySpeed = Math.sin(angle) * blastSpeed
          this.target = getTarget()
          this.ttl = 100
          this.timer = 0
        }
        draw() {
          ctx2.fillStyle = `hsl(${this.hue}, 100%, ${this.lightness}%)`
          ctx2.beginPath()
          ctx2.arc(this.x, this.y, this.size, 0, 2 * Math.PI)
          ctx2.closePath()
          ctx2.fill()
        }
        update() {
          if (this.target) {
            const dx = this.target.x - this.x
            const dy = this.target.y - this.y
            const dist = Math.sqrt(dx * dx + dy * dy)
            const a = Math.atan2(dy, dx)
            const tx = Math.cos(a) * 5
            const ty = Math.sin(a) * 5
            this.size = lerp(this.size, 1.5, 0.05)

            if (dist < 5) {
              this.lightness = lerp(this.lightness, 100, 0.01)
              this.xSpeed = this.ySpeed = 0
              this.x = lerp(this.x, this.target.x + fidelity / 2, 0.05)
              this.y = lerp(this.y, this.target.y + fidelity / 2, 0.05)
              this.timer += 1
            } else if (dist < 10) {
              this.lightness = lerp(this.lightness, 100, 0.01)
              this.xSpeed = lerp(this.xSpeed, tx, 0.1)
              this.ySpeed = lerp(this.ySpeed, ty, 0.1)
              this.timer += 1
            } else {
              this.xSpeed = lerp(this.xSpeed, tx, 0.02)
              this.ySpeed = lerp(this.ySpeed, ty, 0.02)
            }
          } else {
            this.ySpeed += 0.05
            //this.xSpeed = lerp(this.xSpeed, 0, 0.1);
            this.size = lerp(this.size, 1, 0.05)

            if (this.y > c2.height) {
              shards.forEach((shard, idx) => {
                if (shard === this) {
                  shards.splice(idx, 1)
                }
              })
            }
          }
          this.x = this.x + this.xSpeed
          this.y = this.y + this.ySpeed
        }
      }

      class Rocket {
        constructor() {
          const quarterW = c2.width / 4
          this.x = quarterW + Math.random() * (c2.width - quarterW)
          this.y = c2.height - 15
          this.angle = (Math.random() * Math.PI) / 4 - Math.PI / 6
          this.blastSpeed = 6 + Math.random() * 7
          this.shardCount = 15 + Math.floor(Math.random() * 15)
          this.xSpeed = Math.sin(this.angle) * this.blastSpeed
          this.ySpeed = -Math.cos(this.angle) * this.blastSpeed
          this.hue = Math.floor(Math.random() * 360)
          this.trail = []
        }
        draw() {
          ctx2.save()
          ctx2.translate(this.x, this.y)
          ctx2.rotate(Math.atan2(this.ySpeed, this.xSpeed) + Math.PI / 2)
          ctx2.fillStyle = `hsl(${this.hue}, 100%, 50%)`
          ctx2.fillRect(0, 0, 5, 15)
          ctx2.restore()
        }
        update() {
          this.x = this.x + this.xSpeed
          this.y = this.y + this.ySpeed
          this.ySpeed += 0.1
        }

        explode() {
          for (let i = 0; i < 70; i++) {
            shards.push(new Shard(this.x, this.y, this.hue))
          }
        }
      }

      console.log(GetRequest('val').val)
      // INITIALIZATION
      const [c1, c2, c3] = document.querySelectorAll('canvas')
      const [ctx1, ctx2, ctx3] = [c1, c2, c3].map(c => c.getContext('2d'))
      let fontSize = 200
      const rockets = []
      const shards = []
      const targets = []
      const fidelity = 3
      let counter = 0
      c2.width = c3.width = window.innerWidth
      c2.height = c3.height = window.innerHeight
      ctx1.fillStyle = '#000'
      const text = '甜甜,生日快乐！'
      let textWidth = 99999999

      while (textWidth > window.innerWidth) {
        ctx1.font = `900 ${fontSize--}px Arial`
        textWidth = ctx1.measureText(text).width
      }

      c1.width = textWidth
      c1.height = fontSize * 1.5
      ctx1.font = `900 ${fontSize}px Arial`
      ctx1.fillText(text, 0, fontSize)
      const imgData = ctx1.getImageData(0, 0, c1.width, c1.height)
      for (let i = 0, max = imgData.data.length; i < max; i += 4) {
        const alpha = imgData.data[i + 3]
        const x = Math.floor(i / 4) % imgData.width
        const y = Math.floor(i / 4 / imgData.width)

        if (alpha && x % fidelity === 0 && y % fidelity === 0) {
          targets.push({ x, y })
        }
      }

      ctx3.fillStyle = '#FFF'
      ctx3.shadowColor = '#FFF'
      ctx3.shadowBlur = 25

      // ANIMATION LOOP
      ;(function loop() {
        ctx2.fillStyle = 'rgba(0, 0, 0, .1)'
        ctx2.fillRect(0, 0, c2.width, c2.height)
        //ctx2.clearRect(0, 0, c2.width, c2.height);
        counter += 1

        if (counter % 15 === 0) {
          rockets.push(new Rocket())
        }
        rockets.forEach((r, i) => {
          r.draw()
          r.update()
          if (r.ySpeed > 0) {
            r.explode()
            rockets.splice(i, 1)
          }
        })

        shards.forEach((s, i) => {
          s.draw()
          s.update()

          if (s.timer >= s.ttl || s.lightness >= 99) {
            ctx3.fillRect(s.target.x, s.target.y, fidelity + 1, fidelity + 1)
            shards.splice(i, 1)
          }
        })

        requestAnimationFrame(loop)
      })()

      // HELPER FUNCTIONS
      const lerp = (a, b, t) => (Math.abs(b - a) > 0.1 ? a + t * (b - a) : b)

      function getTarget() {
        if (targets.length > 0) {
          const idx = Math.floor(Math.random() * targets.length)
          let { x, y } = targets[idx]
          targets.splice(idx, 1)

          x += c2.width / 2 - textWidth / 2
          y += c2.height / 2 - fontSize / 2

          return { x, y }
        }
      }
    </script>
  </body>
</html>
